Other healthtech apps that were prevented from launching their HealthKit-integrated apps include MyFitnessPal, WebMD and Carrot Fit.

A developer at Carrot Fit told told Cult of Mac that Apple called him to inform him of the problems. "The rep couldn't clarify what was wrong, though users of the app who had already downloaded the update were able to use the HealthKit features without any issue."

The HealthKit platform is set to be one of the key selling points for the much-anticipated Apple Watch. However, if the bug is fixed by the end of September, as Apple claims it will be, then it's unlikely to have an impact on the wearable device's launch in early 2015.